The invention is based on a regulating device for a fuel metering system of the general type for improved regulation of fuel metering. Such so-called lambda regulation systems have long been known, and theoretically they also may generally function satisfactorily. However, aging does occur in such systems, so that as the time in service of the system increases, it is no longer possible for the regulating system to establish an optimal mixture, and incorrect adaptations are accordingly made. Depending upon the load range, these effects of aging of the Lambda sensor and/or of the engine cause greater or lesser errors. Additive errors, for instance, are especially serious during idling and in the lower partial-load range, while multiplicative errors are particularly harmful or disturbing in high load ranges. It is true that the lambda regulation would compensate for these errors when they occur during steady state or normal operation; but during dynamic transitions, that is, transient operating states of the engine the lambda deviation and the duration of the compensation process are both increased as a consequence of aging. During actual vehicle operation, this results in an undesirable worsening of the exhaust-emission values.